In November 1895, German physicist Wilhelm Röntgen was experimenting with a cathode-ray tube when he noticed a screen coated with fluorescent material glowing across the room, even though the tube was covered in black cardboard. What did Röntgen conclude, and what did he do with his discovery?
- He concluded the glow was ordinary visible light leaking through a gap in the cardboard, and he sealed the tube completely, ending his investigation
- He concluded static electricity building up in the room's air was making the screen glow, and he patented a device to safely discharge it
- He concluded the tube was emitting an invisible new form of penetrating radiation, later named X-rays, and he refused to patent his discovery so it could benefit medicine freely
- He concluded the effect was caused by residual heat radiating from the tube's glass, and he sold the finding to a glassmaking company for industrial use
Why C? And why not the others?
Correct answer: C. He concluded the tube was emitting an invisible new form of penetrating radiation, later named X-rays, and he refused to patent his discovery so it could benefit medicine freely
Because the tube was fully covered and no visible light could have escaped, Röntgen reasoned that some invisible, penetrating form of radiation was passing through the cardboard and striking the distant screen; he named it X-rays for their unknown nature, and by placing his own hand between the tube and a photographic plate he produced the first image of living bone. He deliberately declined to patent the discovery so that it could be adopted freely by hospitals everywhere, and he became the first recipient of the Nobel Prize in Physics in 1901. The option describing a light leak is wrong because the cardboard fully blocked visible light and the glow still appeared. The option describing static electricity is wrong because no such discharge-safety patent exists and static buildup does not explain a fluorescent screen glowing at a distance. The option describing residual heat sold to a glassmaker is wrong because heat radiation does not travel through solid cardboard and produce a sharp glow, and no such sale occurred.
Source: Britannica: Wilhelm Conrad Röntgen